Sound amplifier



C. W. HICKS SOUND AMPLIFIER March 7, 1933.

Filed Aug. 9, 1927 avwewto'n Patented Mar. 7, 1933 PATENT OFFICE CHESTERW. HICKS, F HAMPTON, VIRGINIA SOUND AMPLIFIER Application filed August9, 1927. Serial No. 211,755.

This invention relates to sound amplifiers and has for its objectimproved reproduction of sound by the provision of a device applicablefor radio reproduction of sound or for any case where a pulsatingcurrent impulse responsive device may be used to actuate a vibratorydiaphragm to produce sound.

A further object of the invention is to provide a device for producingsound waves and while amplifying these waves to provide a directionalguiding means for all the waves generated.

In the case of the conventional type of small metallic diaphragm as usedin head sets or units for horns, one side of the diaphragm is subjectedto the rebounding waves from a cramped compartment. This producesdistortion which is objectionable especially when amplified. With thesmall metallic diaphragm a horn is necessary to amplify the sound toloud speaker volume and this has its own limitations. The horn type ofspeaker has given away largely to the cone type in which a largediaphragm of parchment is used to produce the desired volume directly.

I have discovered that by moving a diaphragm of blotting paper insliding friction with the air there may be produced sound waves having atone of exceptional quality. I therefore propose to provide a devicecomprising the combination of a pulsating current impulse operateddiaphragm or membrane rolled in such a manner as to present a contour ofa plurality of substantially semicylindrical convolutions. And I mayalso arrange same adjacent to a sound deflector in such relation as toproduce both a directional and amplifying effect on the sound Waves onone or all sides of the moving diaphragm.

With the foregoing and other objects in view, the present inventionconsists in the combination of parts and in the details of constructionhereinafter set forth in the following description and appended claims,certain embodiments of the invention being illustrated in theaccompanying drawing, in which:

Fig. 1 is a diagrammatic view in perspective of the device with thecabinet partially cut away, showing the roll diaphragm and its'relationto the sound deflector.

Fig. 2 is a diagrammatic view in cross sec.- tionthrough the device asshown in Fig. 1.

Fig. 3 is a diagrammatic view similar to 55. Fig. 2 showing a modifiedform of roll diaphragm.

Fig. 4 is a. detail diagrammatic View in side elevation of the diaphragmwith the electromagnetic unit attached thereto.

Referring more particularly to the draW- ing there is shown in Fig. 1 acabinet having sides 4 with a plurality of rearwardly curved interiorfaces 1 forming a partition 2 integral with the remainder of the cabinetand between the two sides 4. The partition is pointed and so formed asto function efliciently as a sound deflector.

The vibrating diaphragm 1 in this invention consists in a suitable typeof fibrous material. Much care must be taken in avoiding the use of onewhich is so thin or light that it would rattle or so thick or dense thatit would fail to amplify low quality tones. I have found certain of thebest grades of blotting paper to be of the most efiicient density,because such blotting paper embodies the necessary low inherentelasticity or capacity for preventing the production ofsound by selfvibration.

Inthe use of such blotting paper, I prefer to employ thesame in itsnormal commercial condition, and without changing or increasing itsdensity as by impregnating the same either in whole or in part with anyagent which would have the effect of increasing the density of theblotting paper in any material degree.

As shownin Fig. 1 the fibrous diaphragm 1' is formed into twoconvolutions of substantially semicylindrical appearance. The twolateral ends of the diaphragm have a suitable rigid non-vibrating member3 slipped over them or otherwise suitably attached to preventinstability of the diaphragm.

' The usual actuating unit such as an electromagnetic unit 6 may beattached to the diaphragm in any suitable manner such asshowndiagrammatically in Fig. 4, in which a clamp 8 and bolt 7 is shownattached at b which may or may not be the vertical center of thediaphragm. It will be observed that the ends a and 0 recede from thevertical line by an amount equal to the angle at. This angle may howeverbe zero degrees. V

Fig. 3 shows a modified form of continuous curved diaphragm roll inwhich the electro-magnetic unit may be connected thereto substantiallyas shown. Theform of the central point of the curved interior faces 1'which form the partition 2 which central point in this instance iscurved instead of pointed is also optional.

The relationsh p of the deflecting partition with curvature effect andthe conformity of the convolutions of the vibratory diaphragm whenactuated by the actuating unit, not only amplifies the radioreproduction of sound but directs the sound waves in the proper channelsin such a manner as to prevent the rebounding of waves against thediaphragm and the consequent distortion in sound reception orreproduction. This is accomplished primarily by means of'the curvatureof the partition or sound deflector 2 which acts as a sound baffle, andits particularv curvatures which extend outwardly past the ends of theroll diaphragm l by a considerable margin. Thus there is derived themaximum efficiency in sound amplification and sound reproduction withthe minimum amount of inherent interference or distortion. 1

- A more specific statement of the foregoing description is that thecurvature of the surfaces 1 of the deflecting partition 2, when taken inconnection with the curvature of the diaphragm 1, forms substantiallytwo opposed spiral structures, each of substantially a singleconvolution, each of which spiral structures has one of the stiffeningstrips 3 for a center. This in effect produces individual spiralstructures in which substantially one half of the spiral convolutionvibrates under the influence of an actuating unit while the other halfof the spiral convolution acts as a deflector and amplifier for thesound waves produced by the vibrations of the first mentioned half ofthe convolution of the spiral. The result of this spiral formation isthe maximum of amplification and deflection of the sound waves withpractically' zero interferenceor distortion.

I claim I 1. A device of the character described including a deflectingpartition having curved facesmeeting each other to form a point and acurved fibrous diaphragm having a stifl'ening member at each of itsextremities, the said deflecting partition when taken in connection withthe curvature of the diaphragm forming substantially two opposed spiralstructures each of substantially a single convolution, and having one ofthe said diaphragm stiflening members for a center, and an actuatingunit connected to said diaphragm, the whole arranged'in such manner thatsubstantially one half of each spiral convolution vibrates under theinfluence of the actuating unit, while the other half of each spiralconvolution deflects and amplifies the sound stiffening member at eachof its extremities,

the said deflecting partition when taken in connection with thecurvature of the diaphragm forming substantially two opposed spiralstructureseach of substantially a single convolution, each ofwhichspiral structures has one of the stifliening'strips for a center and anactuating unitconnected to said diaphragm, the whole arranged in suchmanner that substantially one half of each spiral convolution vibratesunder the influence of the actuating unit, while the other. half of eachspiral convolution deflects andamplifies the sound waves produced by thevibrations of the first mentioned half of each spiral convolution.substantially as described. H

3. A device for the reproduction of sound including a vibratorydiaphragm made of blotting paper whereby it has a low inherentelasticity, said diaphragm beingrolled into two substantially partiallycylindrical formations having central meeting edges, actuating means forimpressing pulsations on'the twopartially cylindrical formations attheir central meeting edges and means for mounting the diaphragm and itsactuatingmeans.

4:. A device of the character described ineluding a flexed vibratorydiaphragm of two roll formations having two edges of the rolls meetingcentrally ofth-e diaphragm for at tachment to an actuating .unit, anda-deflecting partition arranged in rear of the vibratory diaphragm, saiddeflectingpartition having curved faces to receive the sound waves fromthe rear of the diaphragm and deflect the same inthe general directionofthe sound waves from the front of the diaphragm.

In testimony whereof I aifix my signature.

- CHESTER W. HICKS.

